First of all, trust must be earned. It is not a given.
There is probably good reason for you to have broader trust issues. When people repeatedly fail us, we understandably have a hard time trusting new people. So how do we learn to give people a chance?
To start with, find a therapist whose words resonate with you in some way and who you feel relatively comfortable speaking with. Most therapists have a web presence where they write about their approach or philosophy. Many offer a brief initial phone consultation. These are opportunities to get a feel for the person.
If all that seems relatively good, you make an appointment. You still will not trust the therapist, and you should not. You do not know them. They still need to earn it.
A useful way to test how reliable and trustworthy they are is to talk about your issues around trust. See how they respond. Do they seem judgmental? Open-minded? Are they really listening?
If you think they are judging you or not listening, tell them. See how they respond. Are they open to criticism? Do they take in what you are saying?
You cannot force yourself to get over trust issues, nor should you. You may move through them after people prove repeatedly that they are trustworthy. To find that out, you have to give them a chance, and sometimes a second or third chance depending on the situation.
Learning the difference between an honest mistake and someone who is not worthy of your trust takes time, patience, and testing.